1. Field of the Invention
The present invention relates to an illumination system. More particularly, the present invention relates to an illumination system with beam combining function.
2. Description of Related Art
U.S. Pat. No. 5,765,934 has disclosed a light-refracting element applied in a light source in its first embodiment. The light source has a lamp for emitting a beam of luminous flux. The light-refracting element is disposed in the vicinity of the converging point of the beam of luminous flux, and takes the form of a cone. The flat surface of the light-refracting element facing the lamp. The beam of luminous flux is incident on the flat surface, and passes through and is refracted by the light-refracting element. Then, the beam of luminous flux exits from the conical surface of the light-refracting element. Through the refraction effect of the light-refracting element, the beam of luminous flux exiting from the light-refracting element is more uniform. The light-refracting element is applied in the light source with a single lamp, and does not have beam combining function.
U.S. Pat. No. 5,765,934 has also disclosed a reflective prism applied in a light source in its sixth embodiment. The light source has two lamps for emitting two beams of luminous flux. The reflective prism has two opposing reflecting surfaces which are located in the vicinity of the converging points of the two beams, respectively. The two reflecting surfaces reflect the two beams from the lamps to a mirror. Because the reflecting surfaces are located close to the converging points of the two beams where the temperature is high, reflecting films on the reflecting surfaces must be made of the material which resist high temperature, and thus the cost of the reflecting films is high.